Олимпиадный тренинг

Задача 21716. Sum of numbers from 1 to n


Задача

Темы: Рекурсия
Write a program containing a recursive function that  solves the problem of finding the sum of numbers from 1 to n (n <= 100)
You cannot use cycles and the formula for the sum of an arithmetic progression in the program
The main program must contain initial data input, function call and response output
The input to the program is a number n

Examples
# Input Output
1 5 15

Запрещенные операторы:for;while;until